Vacuum X-ray envelope

ABSTRACT

An opaque vinyl envelope having facing polished inner surfaces and an open edge into which an intensifier screen and X-ray film are inserted. The other three edges are completely sealed except for a valve at one edge. Reinforcing strips are attached along the open edge. The three sealed edges of the envelope are heat sealed without pressure to eliminate an internal bead and minimize leakage along the bead when the open edge is closed and the envelope evacuated. An insert that has a relatively rough surface or is pourous assures full evacuation.

REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part to co-pending patentapplication Ser. No. 438,033 filed Jan. 30, 1974 .Iadd.nowabandoned.Iaddend..

BACKGROUND OF THE INVENTION

This invention relates in general to a vacuum cassette to be used in thetaking of X-rays where an intensifer screen is employed.

When taking an X-ray, it is known to place the unexposed film next to anintensifier screen so as to increase contrast and thus make possiblelower X-ray intensity to minimize patient exposure to X-rays. To obtaineffective use of the intensifier, it is important that the unexposedX-ray film be held tightly against the intensifier screen. It is knownto achieve this result by placing the film and intensifier screentogether in a vinyl envelope, apply a vacuum to the inside of theenvelope to collapse the sides of the envelope onto the X-ray film andintensifier screen thereby holding film and screen tightly together.While the vacuum is applied, the open edge of the envelope is heat orpressure sealed and the resulting four-ply sandwich is then ready foruse. This loading of the envelope, application of vacuum and sealingmust all take place in a darkroom so that the film is not exposed duringthe process. Special equipment for use in the darkroom is required toeffect this known process and the envelope employed can only be usedonce.

It is a purpose of this invention to provide a simpler, less timeconsuming and less expensive technique for producing the vacuumcassette.

A further purpose of this invention is to provide a technique whichpermits reusing the envelope.

Another purpose to this invention is to provide a structure that assuresfull evacuation across the entire face of the X-ray film and intensifierscreen.

BRIEF DESCRIPTION OF THE INVENTION

In brief, this invention is in an opaque vinyl envelope having interiorpolished faces and an open edge into which the intensifier screen andX-ray film are inserted. The other three edges are completely sealedexcept for a valve preferably located at a side edge near a cornerremoved from the open edge. A separate reinforcing strip is attached toeach envelope sheet along the open edge. A spacer inside the envelopeadjacent to the valve inlet aids in preventing the highly flexible vinylsheet material from immediately collapsing around the valve; collapsewhich might prevent thorough evacuation of the entire envelope.

More importantly, a heavy paper sheet is folded over to provide a holderwithin which the film and screen are placed. The fibrous folder assuresthat there will be complete evacuation and eliminates trapping pocketsof air during evacuation.

In use, the intensifier screen and unexposed X-ray film are placed faceto face inside the folded over paper holder within the envelope in adarkroom. The operator then slips a clamp along the reinforcing stripsat the open edge to seal the envelope. The resultant filled envelope isthen taken out of the darkroom and the valve attached to a source ofvacuum. After the vacuum has been applied so that the envelope collapsesto hold the intensifier screen and X-ray film tightly together, thevalve is closed and the vacuum removed. The result is a cassette readyfor use.

The normal sealing of the vinyl envelope leaves an interior bead whichtends to provide a passage for air from the outside into the envelope.This leakage problem is substantially eliminated by a zero pressurecontact heat sealing process for sealing the side edges of the envelopethereby eliminating the bead and the path for air leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the positioning of the intensifierscreen, X-ray film and holder for insertion into the vinyl envelope.

FIG. 2 is a cross-sectional view along the line 2--2 of FIG. 1 showingthe screen, film and holder inserted therein and the open edge clamped.

FIG. 3 is a view similar to that of FIG. 2 with the envelope evacuatedand thus ready for use.

FIG. 4 is a cross-sectional view along the line 4--4 of FIG. 3.

FIGS. 5 and 6 are cross-sectional views through the valve showing thevalve, respectively, open and closed.

FIG. 7 illustrates the method of sealing the sealed edges of the FIG. 1envelope.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the FIGS., an opaque, preferably black, patent plasticenvelope 10 has sealed edges 12, 13 and 14. The envelope material can bevinyl, polyethylene or other thermoplastic polymer. The edge 16 is openso that the unexposed X-ray film 18 and the intensifier screen 20 withina folded heavy paper holder 21 can be inserted into the envelope 10through the mouth of open edge 16. In one embodiment where theintensifier screen and X-ray film is about 10 inches long, the length ofthe envelope 10 from edge 16 to edge 14 is 121/2 inches. The envelope isabout 11/2 inches wider than the screen 20 and film 18 to facilitateinsertion of film and screen.

Two reinforcing strips 22, 23 each 1/2 inch wide and 50 mil (0.050 inch)thick are sealed to the sheets 10a, 10b of the envelope 10 adjacent tothe open edge 16. One strip 22 includes thumb holes 42 to facilitateopening the envelope. After the X-ray film 18 and intensifier screen 20within the paper folder 21 are placed in the envelope 10 in thedarkroom, the operator can simply, by feel, locate the reinforcingstrips 22, 23 and slip a plastic C-shaped claim 25 over the strip (seeFIGS. 2 and 3) to seal the envelope 10. The plastic out of which theC-clamp 25 is made can be of a resilient material such as polystyreneand dimensioned to provide an interference type fit between clamp 25 andthe four plies of strips 22, 23 and envelope sheets 10a, 10b.

The valve 30 is preferably an automatic check-type valve with a standardautomobile tire type core 32. The Roberts valve type No. 40-AO has beenfound effective. It is important that the valve 30 have a stem 34 whichmaintains its normally closed position until or unless a properly matingvacuum hose coupler is inserted to depress the stem 34 and to hold itdepressed while the interior of the envelope 10 is evacuated. Once theevacuation is completed, the removal of the vacuum hose coupler releasesthe spring-loaded stem 34 into its normally closed position thusassuring an air-tight seal.

The valve 30 is mounted in a vinyl tube 36, which tube 36 in turn ishermetically sealed to the envelope sheets 10a, 10b. A cylindrical vinylreinforcing insert 38 keeps the vinyl segment from collapsing around thevalve 30 when a vacuum is drawn. The vinyl tube 36 is approximately oneinch long and provides a finger hold for the technician when connectingthe vacuum hose coupler to the threaded portion 40 of the valve 30.

Alternate to the reinforcing tube 38, a sponge filling the vinyl tube 36inward of the valve 30 can be used to assure that communications withthe interior of the envelope 10 is maintained throughout evacuation.

It is preferable that the width of the envelope 10 be at least one inchgreater than the width of the film. This will facilitate loading andunloading and increase the likelihood that the technician will simplydrop the film in rather than put his hand into the envelope when loadingthe envelope.

In use, the operator in a darkroom slips the C-clamp 25 over the openedge 16 to create the condition shown in FIG. 2. Then outside thedarkroom the valve 30 is connected to a source of vacuum and theenvelope evacuated to the condition shown in FIG. 4. The source of thevacuum is then disconnected and the cassette is ready for use.

After use, the cassette is taken into a darkroom, the C-clamp 28 slippedoff, the envelope opened and the folder 21 containing the X-ray film 18and intensifier screen 20 taken out. The envelope 10 can then be usedagain, as can the intensifier screen 20 and the above-describedoperation repeated. Openings 42 in the strip 22 provide a means tofacilitate opening the envelope.

As may be seen in FIG. 7, a paired two sheets of 10 mil (0.010 inch)thick vinyl are positioned on a surface 50. Along the side edges 13 and14, an L-shaped hold down attachment 52 is positioned. The two sheets10a, 10b of the envelope 10 are each ten mils thick and are polishedsurface material known in the trade as patent plastic. When ordered aspatent plastic, the material comes in a two-sheet thick roll in whichthe two polished surfaces face one another. An appropriate length ofthis material is cut and placed on the surface .[.40..]. .Iadd.50..Iaddend.Thus, the two polished surfaces become the interior faces ofthe envelope 10. Where two ten mil sheets are employed, the hold downfixtures 52 provide a hold down space above the surface 50 of exactlytwenty mils so that a nil amount of pressure is exerted on the edges 12and 13 of the envelope sheets. Heat is then applied through the heatconducting L-shaped hold down fixtures 52 so that the edges 12 and 13are sealed. The portion of the edge 13 to which the valve 30 is attachedis sealed separately. The purpose of this arrangement with respect tothe carefully dimensioned hold down and sealing fixtures 52 is to assurethat there will be no head along the inner edges 12 and 13, or, atleast, that there will be no such bead along these edges at the portionof the envelope 10 near the open edge 16. Thus, when the open edge 16 isclamped shut, the sheets will lay very flat along the entire length ofthe open edge 16 and there will be no bridging due to any bead that mayexist along the inner side edges 12, 13 and thus the risk of air leakinginto the evacuated cassette along such a bridge is substantiallyeliminated.

The absence of a bead together with the facing interior polished plasticsurfaces creates a leak-proof envelope. The vacuum is held because thesetwo features combine to assure no paths for air leakage.

It is believed that these highly-polished facing surfaces are effectiveto assure a long-lasting vacuum in the cassette because when forcedtogether during evacuation, they adhere to one another so completely asto seal off the portion of the interior of the cassette between openedge 16 and film from the outside air in a fashion that eliminates allpossible air paths.

When the facing surfaces are not highly polished, there is no tendencyfor them to adhere other than that created by the outside pressureexerted when the vacuum is taken. But, to the extent that there are anyminiscule air pockets or air paths between the nonpolished facingsurfaces, there is provided a path for air to leak in and once suchleakage starts, the entire vacuum is rapidly destroyed.

However, the good sealing quality of the polished surfaces creates theproblem that during evacuation local air bubbles are formed. Pockets ofair can be encapsulated as the vinyl collapses around a local area. Thisproblem arose over the surface of the film 18 or screen 20 when thefolder 21 is not used. Thus a roughened surface or fibrous insert hasbeen found necessary to assure air paths during evacuation thateliminate air bubbles and thus assure the desired complete and evenevacuation across the entire surface of the film 18 and screen 20.

The heavy paper folder 21 serves this air path providing function. Afibrous, preferably rough surface, material thus prevents the trappingof air bubbles over the surface of the film and/or screen and thusassures a complete and even texture across the whole surface of thescreen and film.

A heavy paper folder 21 is a preferred insert because it provides theadditional convenience of a folder in which to hold the film and screenand to keep them in line. It is an aid in inserting the film and screen.However, the folder could be eliminated if the intensifier screen 20were laminated to a cardboard back and two intensifier screens used oneither side of the X-ray film as is common practice. The cardboard backwould have the same function of providing air paths across the surfaceof the screen. Accordingly, it should be understood herein that the terminsert is used to refer to two ply arrangement which may be, andpreferably is, a single folded separable insert.

In one embodiment a 240 weight white coronado texture paper, supplied bythe Milton Paper Company of 100 West 22nd Street, New York, N.Y., wasused and found effective.

The two reinforcing strips 22, 23 are important to insure a reasonablelife for this reusable envelope 10. These reinforcing strips prevent thedeformation of the thin collapsible sheets 10a, 10b near the open edge.[.12..]. .Iadd.16. .Iaddend.Any such deformation would result in thesheets not lying perfectly flat against one another when closed and thuswould prevent providing air tight seal. The reinforcing strips 22, 23 bypreventing deformation, assure that the two sheets will lie perfectlyflat against one another at the open edge, when closed, and thus serveto assure the obtaining and maintenance of the vacuum after repeateduses of the envelope 10.

What is claimed is:
 1. A reuseable envelope for an X-ray cassette havingX-ray film and intensifier screen comprising:first and secondcollapsible sheets sealed to one another along first, second and thirdsealed edges forming an envelope having an open edge, a sealing zoneextending across said open edge between said first and second sealededges, said sheets having polished facing interior surfaces in saidsealing zone, said interior surfaces in said sealing zone being flushagainst each other at the line of the seal at said first and secondsealed edges, the seal at said first and second sealed edges beingbeadless in said sealing zone, and a valve sealed to one of said sealededges permitting communication between the interior of said envelope andthe outside, said valve being positioned away from said sealing zone. 2.The envelope of claim 1 further comprising:first and second flat insertportions, each of said portions having a surface large enough tosubstantially cover the surface area of whatever X-ray film andintensifier screen is used, said insert portions providing air pathsacross the surface of said insert portions to said valve said first andsecond collapsible sheets being large enough to accommodate said insertportions within said envelope in a position removed from said sealingzone.
 3. The envelope of claim 1 further comprising:a spacer elementinside said envelope adjacent to the port of said valve and providing aseparation between said sheets of said envelope adjacent said valve. 4.The envelope of claim 2 further comprising:first and second reinforcingstrips along the edge respectively of said first and second collapsiblesheets at said open edge.
 5. The envelope of claim 4 furthercomprising:a resilient C-clamp dimensioned to fit along said reinforcingstrips.
 6. The envelope of claim 1 further comprising:first and secondreinforcing strips along the edge respectively of said first and secondcollapsible sheets at said open edge.
 7. The envelope of claim 6 furthercomprising:a spacer element inside said envelope adjacent to the port ofsaid valve and providing a separation between said sheets of saidenvelope adjacent said valve.
 8. The enveope of claim 6 furthercomprising:a resilient C-clamp dimensioned to fit along said reinforcingstrips.
 9. The method of sealing edges of a two collapsible sheetenvelope having an open edge to provide a vacuum retaining .[.cassett.]..Iadd.cassette .Iaddend.for X-ray film and intensifier screen containedtherein comprising the steps of:placing an edge of two sheets ofcollapsible material having facing polished surfaces between and incontact with heat conducting members at substantially nil pressure, andapplying heat to said sheets through said members of seal said edge. 10.The method of claim 9 wherein said sheets are of a thermoplasticpolymer. .Iadd.
 11. A reuseable envelope for an X-ray cassette havingX-ray film and intensifier screen comprising:first and secondcollapsible sheets sealed to one another along first, second and thirdsealed edges forming an envelope having an open edge, a sealing zoneextending across said open edge between said first and second sealededges, said sheets having polished facing interior surfaces in saidsealing zone, said interior surfaces in said sealing zone being flushagainst each other at the line of the seal at said first and secondsealed edges, the seal at said first and second sealed edges beingbeadless in said sealing zone, and a valve sealed to said envelope, saidvalve permitting communication between the outside and the interior ofsaid envelope apart from said sealing zone. .Iaddend..Iadd.
 12. Theenvelope of claim 11 further comprising: first and second flat insertportions, each of said portions having a surface large enough tosubstantially cover the surface area of whatever X-ray film andintensifier screen is used, said insert portions providing air pathsacross the surface of said insert portions to said valve, said first andsecond collapsible sheets being large enough to accomodate said insertportions within said envelope in a position removed from said sealingzone. .Iaddend..Iadd.
 13. The envelope of claim 11 further comprising: aspacer element inside said envelope adjacent to the port of said valveand providing a separation between said sheets of said envelope adjacentsaid valve. .Iaddend..Iadd.
 14. The envelope of claim 12 furthercomprising: first and second reinforcing strips along the edgerespectively of said first and second collapsible sheets of said openedge. .Iaddend..Iadd.
 15. The envelope of claim 14 further comprising: aresilient C-clamp dimensioned to fit along said reinforcing strips..Iaddend..Iadd.
 16. The envelope of claim 11 further comprising: firstand second reinforcing strips along the edge respectively of said firstand second collapsible sheets at said open edge. .Iaddend..Iadd.
 17. Theenvelope of claim 16 further comprising: a spacer element inside saidenvelope adjacent to the port of said valve and providing a separationbetween said sheets of said envelope adjacent said valve..Iaddend..Iadd.
 18. The envelope of claim 16 further comprising: aresilient C-clamp dimensioned to fit along said reinforcing strips..Iaddend.